Method for inspecting defect and apparatus for inspecting defect

ABSTRACT

The present invention is an apparatus for inspecting foreign particles/defects, comprises an illumination optical system, a detection optical system, a shielding unit which is provided in said detection optical system to selectively shield diffracted light pattern coming from circuit pattern existing on an inspection object and an arithmetic processing system, wherein said shielding unit comprises a micro-mirror array device or a reflected type liquid crystal, or a transmission type liquid crystal, or an object which is transferred a shielding pattern to an optical transparent substrate, or a substrate or a film which is etched so as to leave shielding patterns, or an optical transparent substrate which can be changed in transmission by heating, sudden cold, or light illumination, or change of electric field or magnetic field, or a shielding plate of cylindrical shape or plate shape.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.10/724,750, filed Dec. 2, 2003, now U.S. Pat. No. 7,248,352 which is aContinuation-In-Part of U.S. application Ser. No. 10/722,531, filed Nov.28, 2003, now U.S. Pat. No. 7,315,363 and is related to U.S. applicationSer. No. 11/605,239, filed Nov. 29, 2006, which is a Continuation ofU.S. application Ser. No. 10/722,531, the contents of which are allincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method for inspecting defect and anapparatus for inspecting defect in a production line for a semiconductordevice, liquid crystal, magnetic head, or other device, and moreparticularly to a technology for inspecting foreign matters(particle)/defects existed on a processing substrate formed circuitpatterns.

An example of semiconductor wafer inspection will now be described.

In a conventional semiconductor manufacturing process, any foreignmatter existing on a semiconductor substrate (wafer) may cause a wiringinsulation failure, short circuit, or other failure. Furthermore, sincethe semiconductor elements have turned minutely, when a fine foreignmatter exists in the semiconductor substrate, this foreign matter causesfor instance, insulation failure of capacitor or destruction of gateoxide film or etc. These foreign matters are mixed in the semiconductorsubstrate by various causes in the various state. As a cause ofgenerating of the foreign matters, what is generated from the movablepart of conveyance equipment, what is generated from a human body andthe thing by which reaction generation was carried out by process gaswithin processing equipment, the thing currently mixed in medicine ormaterial used can be considered. A liquid-crystal display device willbecome what cannot be used, if a foreign matter mixes on a circuitpattern or a certain defect produces a liquid-crystal display devicemanufacturing process similarly. The situation of the same is said ofthe manufacturing process of a printed circuit board, and mixing of theforeign matter becomes the short circuit of a pattern, and the cause ofpoor connection.

A certain conventional technology for detecting the above-mentionedforeign matters (particles) on a semiconductor substrate, which isdisclosed, for instance, by Japanese Patent Laid-open No. 62-89336,illuminates laser light to the semiconductor substrate, detects thelight scattered from any foreign matter on the semiconductor substrate,and compares the obtained result against the inspection result of thelast inspected semiconductor substrate of the same type to conduct ahigh-sensitivity, high-reliability, foreign matter/defect inspectionwhile averting a pattern-induced false alarm.

As one of the technology which detects the foreign matter on thisconventional kind of semiconductor substrate, as indicated by a priorart 1 (Japanese Patent Laid-open No. 5-218163), loses the misreport bythe circuit pattern, and it enables inspection of the foreign matterwith the defect high sensitivity and the high reliability, byilluminating laser beam to the semiconductor substrate, detecting thescatter light generated from the foreign matter when the foreign matteris adhered on the semiconductor substrate and comparing with theinspection result of the semiconductor substrate of the same kindinspected immediately before.

Moreover, one of technology of inspecting the above-mentioned foreignmatter is known a method for illuminating coherent light to the wafer,removing the light ejected from the repetition circuit pattern on thewafer by a spatial filter, and emphatically detecting the foreign matterand the defect without repetition nature. The foreign matter inspectionapparatus which illuminates light from a direction angled 45 degrees forthe main straight line groups of this circuit pattern to the circuitpattern formed on the wafer and does not input 0-orderdiffraction lightfrom main straight line groups into an opening (a pupil) of an objectivelens, is known by a prior art 2 (Japanese Patent Laid-open No.1-117024).

Prior arts relating with an apparatus and a method for inspecting thedefect of the foreign matter or the like are known as a prior art 3(Japanese Patent Laid-open No. 1-250847), a prior art 4 (Japanese PatentLaid-open No. 6-258239), a prior art 5 (Japanese Patent Laid-open No.6-324003), a prior art 6 (Japanese Patent Laid-open No. 8-210989) and aprior art 7 (Japanese Patent Laid-open No. 8-271437).

SUMMARY OF THE INVENTION

As indicated on the prior arts, on an apparatus for inspecting variouskinds of minute circuit patterns including semiconductor device,although spatial filtering is separated efficiently between the signalbeing generated from the defect and the signal (pattern noise) beinggenerated from the circuit pattern, number of diffraction light beinggenerated from the pattern which can shield was restricted since theshielding plate with wide width was used from the problem of mechanicalaccuracy.

An object of the present invention can detect a foreign matter defect inhigh sensitivity by highly precise spatial filtering, on a technologyfor inspecting the minute (fine) circuit pattern by using images beingformed by illuminating white light, single wavelength light or laserlight to the minute (fine) circuit pattern.

In order to attain the object, the present invention is provided (1) amicro-mirror array device or a reflected type liquid crystal, or (2) atransmission type liquid crystal, or (3) an object which is transferreda shielding pattern to an optical transparent substrate, or (4) asubstrate or a film which is etched so as to leave shielding patterns,or (5) an optical transparent substrate which can be changed intransmission by heating, sudden cold, or light illumination, or changeof electric field or magnetic field, or (6) a shielding plate ofcylindrical shape or plate shape.

In order to attain the another object, the present invention is provideda function which is changed the shielding pattern according to patternchange of diffraction light resulting from the difference in the formfor every place of the circuit pattern which exists on the surface ofthe inspection object.

In order to attain the further another object, the present invention isprovided a function which is changed according to at least two or morediffraction light patterns in pattern change of diffraction lightresulting from the difference in the form for every place of the circuitpattern which exists on the surface of the inspection object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing an outline composition of an inspectionapparatus which used a spatial filtering.

FIG. 2 is an front view showing 1st embodiment of a spatial filter (anobject using a plurality of shielding plates and two springs of rightwind)

FIG. 3 is an front view showing 2nd embodiment of a spatial filter (anobject being combined a shielding plate and two springs of right windand left wind).

FIG. 4 is an front view showing an etching plate.

FIG. 5 is an front view showing 3rd embodiment of a spatial filter(transmission type liquid crystal).

FIG. 6 is an front view showing 4th embodiment of a spatial filter(micro mirror array device).

FIG. 7 is a comparison diagram of the transmission type liquid crystaland the micro mirror array device.

FIG. 8 is a front view showing an outline composition of an inspectionapparatus on case of using the micro mirror array device as a spatialfiltering unit.

FIG. 9 is a front view showing 1st embodiment of the micro mirror arraydevice.

FIG. 10 is a front view showing 2nd embodiment of the micro mirror arraydevice.

FIG. 11 is a front view showing an outline composition of an inspectionapparatus which a plurality of spatial filtering units are used.

FIG. 12 is a front view of a Fourier optical system showing an opticalpath diagram of the Fourier optical system.

FIG. 13 is a front view of a Fourier optical system showing an opticalpath diagram of an optical system which observes a Fourier transformplane.

FIG. 14 is a figure showing a tip (a die) layout.

FIG. 15 is a diagram which compares diffraction patterns on each tiparea with optimal shielding patterns.

FIG. 16 is a figure showing 1st embodiment of the inspection method.

FIG. 17 is a figure showing 2nd embodiment of the inspection method.

FIG. 18 is a figure showing 3rd embodiment of the inspection method.

FIG. 19 is a figure which compares between composition of spatial filterof right wind spring system and composition of spatial filter of rightwind spring and left wind spring combination system, and between filterinclinations on each of spatial filters.

FIG. 20 is a plane view of a tip showing scanning path example of onetip (one die) which an image sensor is imaged.

FIG. 21 is the figure showing diffraction patterns for each area andcorrespondence position relations in the tip.

FIG. 22 is a figure showing one embodiment of setting method of thefilter pattern.

FIG. 23 is a figure showing one embodiment of setting method ofinspection conditions.

FIG. 24 is a figure showing another embodiment of setting method of thespatial filter.

FIG. 25 is a figure showing pattern signals at the time of un-usingit/at the time of using space filter.

FIG. 26 is a block diagram showing one embodiment of improvement systemin the yield of the semiconductor device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the accompanying drawings.

FIG. 1 is a schematic diagram illustrating one embodiment of aninspection apparatus according to the present invention. This inspectionapparatus is suitable for inspecting foreign matters and defects. Asshown in the figure, the inspection apparatus comprises an illuminationsystem unit 100, a detection optical system unit 200, a stage system300, an arithmetic processing system 400, a wafer observation unit 500(monitor 500), a Fourier transform plane observation optical unit 600,and a wafer observation optical system 700. The illumination system 100comprises a laser oscillator 101, a wavelength plate 102, beam expanders103, 104 for varying the laser spot size, an aperture diaphragm 105 anda cylindrical lens 106. The wavelength plate 102 varies the degree ofillumination light polarization. The beam expanders 103, 104 vary theillumination size (illumination area). A mirror (not shown) varies theillumination angle. The cylindrical lens 106 is used to illuminate anobject under inspection with one side reduced.

The illumination system unit 100 is illuminated a slit-shaped beam spoton a wafer 1. The cylindrical lens 106 is used to reduce the size of anillumination light beam to match a receiving field of a line sensor (CCDor TDI) 205, which is coordinated with the wafer surface for imageformation purposes. This also results in efficient use of illuminationenergy. The cylindrical lens 106 is equipped with an optical systemwhich rotates to provide the same condensation for the front and rearsides of illumination when the light is illuminated from a directionhaving an angle of θ1 for major straight line group of a circuit patternformed on the object under inspection. Instead of the cylindrical lens,a cone lens (conical lens) described, for instance, by Japanese PatentLaid-open No. 2000-105203 (equivalent to U.S. patent Ser. No.09/362,135), may be alternatively used. A slit light beam, which isincident on the wafer surface at an inclination angle of α to thehorizontal, bounces off the wafer's surface layer and scatters. A wafer1 is inspected by running a relative scan over the stage system 300 anddetection optical system unit 200. As indicated in FIG. 1, the detectionoptical system unit 200 mainly comprises a Fourier transform lens (whichhas a function as an objective lens) 201, an inverse Fourier transformlens (which has a function as an image forming lens) 202, and an imagesensor 205, and is capable of inserting a spatial filter 2000 into aFourier transform plane in an optical path. Alternatively, lens 201 maycomprise an objective lens and a Fourier transform lens. Lens 202 mayalternatively comprise an inverse Fourier transform lens and an imageforming lens. In addition, the inverse Fourier transform lens 202 isvertically movable as indicated by an arrow mark so that themagnification can be changed.

Further, an optical path branching device 601 such as a mirror or beamsplitter and a Fourier transform plane observation optical unit 600 canbe inserted into an optical path. The Fourier transform planeobservation optical unit 600 is equipped with a convex lens 602 and a TVcamera 605 for observing a pattern in the Fourier transform plane. Theconvex lens 602 is movable as indicated by an arrow mark so that imagesof the Fourier transform plane and wafer surface can be formed by the TVcamera 605. The signal output from the TV camera 605 enters thearithmetic processing system 400. The detected light, which is derivedfrom the wafer 1, is passed through the inverse Fourier transform lens202 and optical path branching device 601, polarized by a polarizingplate 203, adjusted by a light intensity adjustment plate 204 to varyits intensity, and incident on the image sensor 205. The light is thenconverted into an electrical signal by the image sensor 205, and theresulting electrical signal enters the arithmetic processing system 400.Light diffractions generated from edges of repetitive circuit patternsof the wafer surface are condensed (interfered) into a condensed lightpattern (an interference pattern) having regular pitch in the Fouriertransform plane. A spatial filter 2000 is set according to the condensedlight pattern (the interference pattern) so that the diffracted lightgenerated from the edges of the repetitive patterns do not reach theimage sensor 205. Meanwhile, it is known that a Fourier image of foreignmatter (particle) or defect is not regular and distributes irregularlyin the Fourier transform plane. As a result, the light scattered fromforeign matter and defects is partly shielded by the spatial filter;however, its greater part reaches the image sensor 205. Thus, by settingthe spatial filter 2000 according to the condensed light pattern in theFourier transform plane of the detection optical system unit 200, sincethe greater part of the scattered light of foreign matter and defects isreceived by the image sensor 205 so that the scattered light (thediffracted light) of the circuit pattern is removed, it becomes possibleto detect the foreign matter/defect in high sensitivity by improving aS/N ratio. Since the detection lens of the detection optical system unit200 is provided with a zoom optical system or an objective lens selectormechanism, it is possible to change the detection magnification. Since adetection pixel size (when they are converted to equivalent values forthe wafer surface) becomes small in high magnification mode, it possibleto detect the minute foreign matter/defect at a high sensitivity byimproving the S/N ratio. However, the inspection speed is low becausethe detection pixel size are small. On the other hand, by enlarging thedetection pixel size in a low magnification mode, inspection speedbecomes early and, as a result, it is possible to inspect many waferswithin a predetermined period of time. Since a plurality ofmagnification modes are available, it is possible to use the modesselectively to conduct a low-magnification, high-speed inspection on aproduct/process to which loose design rules are applied, and ahigh-magnification, high-sensitivity inspection on a product/process towhich severe design rules are applied. The signal acquired by the imagesensor 205 is subjected to data processing within the arithmeticprocessing system 400 to output a foreign matter/defect candidate. Theresult of foreign matter/defect detection is stored as electronic dataon a recording medium within the apparatus or in a defect managementsystem 82 as shown in FIG. 26 in the network-connected server unit.

A wafer ID (kind name, process name) and its recipe are entered in arecipe management system (not shown) within the server unit. Asdescribed later, the recipe contains an illumination light intensityvalue, illumination polarized light setting, illumination irradiationangle α setting for horizontal surface, illumination irradiationdirection θ1 setting for the layout directions of the chips, detectionvisual field size, selected spatial filter data, and detection polarizedlight setting. A production line management system (not shown) withinthe server unit displays data to indicate whether the apparatus isconducting an inspection or on standby and indicate what is flowing on aproduction line. The defect management system 82 manages and displaysthe inspection result of the previous process.

The stage system 300 uses a stage controller 306 to control an X-stage301, a Y-stage 302, a Z-stage 303, and a θ-stage 304 for the purpose ofplacing the wafer 1 in a specified position and at a specified height.

The foreign matter/defect inspection result displays on the monitor 500.

The scattered light from a wafer 1 passes the Fourier transform lens201, and it is constituted so that the image of the wafer may image tothe image sensor plane. The scattered light generated from therepetition pattern has a periodical light intensity distribution.Therefore, the diffraction image according to a repetition pitch of apattern is imaged on the Fourier transform plane of a lens 201. On theother hand, since light intensity distribution of scattered lightgenerated from the defect generally consists of random frequencycomponents, the image of the scattered light does not image on theFourier transform plane. So, by shielding the diffraction lightgenerated from the repetition circuit pattern on a wafer 1 with thespace filter 2000, the great portion of scattered light generated fromthe circuit pattern can be shielded, and, on the other hand, the greatportion of scattered light generated from the defect can be passed. Onthis result, the scattered light from the circuit pattern is removed andthe scattered light from the defect is only imaged on the image sensor205, and it becomes possible to acquire the signal of the defect by thehigh S/N ratio.

Now, since the shielding plate is the purpose to shield the diffractionlight, it is necessary to make widths of shielding portion of theshielding plate larger than widths of the diffraction light. Moreover,since the size of the opening of the Fourier transform plane is limitedsize decided by the design of a lens, the maximum number of spatialfilters become settled by (Fourier transform plane openingdiameter)÷(filter width). Since the filter which had width large enoughcompared with the width of the diffraction light was used from theproblem of machine accuracy with conventional equipment, there were fewnumbers of the shielding plate. Therefore, this spatial filter with fewnumbers of the shielding plates cannot shield only the diffraction lightof the repetition circuit pattern below 5 mm pitch on the wafer.Consequently, the diffraction light generated from the patterns of SRAMarea, CCD circuit and a liquid crystal circuit on where the patternpitch are large, could not shield only a part of the diffraction light.

In the present invention, it made it possible to position with highprecision by changing structure of the spatial filter. It made itpossible to become possible to narrow filter width, to use many numbersof filters, and to shield diffraction light generated from repetitionpattern below 25 mm pitch by it.

FIG. 2 is shown a 1st embodiment 2100 of a shielding mechanism (aspatial filter). A plate 2111 is soldered to helix springs (clockwisetwining spring-clockwise twining spring) 2101. This uses expanding andcontracting with sufficient accuracy according to the law of a hookwithin the limits of elastic modification of a spring. If the shieldingmaterial 2111 is attached in the portion to which two springs 2101correspond, the pitch of a filter can be changed with sufficientaccuracy by making two springs 2101 expand and contract simultaneously.When shown in FIG. 2, two springs 2101 are constituted by a clockwisetwining spring and a clockwise twining spring.

Soldering, adhesion material, welding, etc. can be considered as thetechnique of attaching (joining) the shielding material 2111 to thespring 2101. Although it can weld when the filter (the shieldingmaterial) 2111 and the spring 2101 are thick, when the filter 2111 andthe spring 2101 become thin, in case it is welding, the attachmentbecomes difficult in order that the filter or the spring may melt.Therefore, when the filter 2111 and the spring 2101 become thin, solderand adhesives are good.

FIG. 4 is a figure showing what created the shielding plate 2111 in thestate with frame 2110 using etching. A frame 2110 will be separated andremoved after attaching the shielding plate 2111 to the spring finally.It is easy to solder the way whose thickness of an attachment part ofthe shielding plate is the almost same thickness as the diameter of thespring. Moreover, since the thickness of the shielding plate 2111 isdecided from the condensed diameter of the diffraction light, and themachine accuracy of a filtering unit, the thickness of the shieldingplate may differ between the attachment part and the shielding position.In such a case, in order to prevent concentration of the mechanicalstress at the time of spring expansion and contraction, and the heatstress at the time of solder attachment, it is desirable to carry outcurvature forming, as shown in an enlargement figure of FIG. 4.

On case of that the springs of the same wining direction are used asshown in FIG. 2, when the springs are made to expand and contract, thestress generated between the filters and the springs poses a problem. Itis possible to negate the stress generated on both sides of theshielding material by combining a clockwise twining spring and acounterclockwise twining spring, and to further attain the highprecision.

FIG. 3 is a figure showing a 2nd embodiment 2200 of the spatial filterwhich combined the clockwise twining spring 2101 and thecounterclockwise twining spring 2102. The graph of FIG. 19 is shown byplotting inclinations of the shielding plate 2111 for filter number whenthe filter springs make to expand and contract. Consequently, it canunderstand that the accuracy of a filter is improving by using thesprings 2101, 2102 which are differ mutually the twining direction.

As the spatial filter, it is possible to use a transmission type liquidcrystal 2300 and a micro-mirror array device 2400, etc. besides thecombination of the springs and shielding material.

FIG. 5 is shown the transmission type liquid crystal 2300 which is a 3rdembodiment of the spatial filter. Since the transmission and theshielding of light can be chosen by setting up ON and OFF for everypixel, the flexibility of shielding pattern generation becomes highcompared with the above spring-type spatial filter. Generally, althoughthe liquid crystal device will fall off light amount since polarizationis used, the measure is possible for the liquid crystal device byraising the intensity of illumination light.

Moreover, generally, as shown also in FIG. 7, since the liquid crystaldevice has a drive circuit for every pixel, it has the problem that therate of opening is low. As the lowness of the rate of opening causes thefall of transmission rate and the diffraction phenomena in the latticeof the liquid crystal pixel, it is desirable to use a liquid crystaldevice that the rate of a opening is high as much as possible (at least60% or more). On the other hand, when it thinks from a viewpoint of ashielding function, the transmission rate at the time of shielding haslower possible desirable one. Although the contrast of a liquid crystaldevice is defined by generally taking the ratio of the transmissionlight amount at the time of transmission and the transmission lightamount at the time of shielding, it is desirable that the value of thecontrast is 800:1 or more.

FIG. 6 is a micro-mirror array device (a digital micro-mirror device(DMD)) 2400. Since the micro-mirror array device is generally 80% ormore of high opening rate, the attenuation of light amount and theinfluence of diffraction in the lattice of the liquid crystal pixel, arelow than the transmission type liquid crystal device. Consequently, themicro-mirror array device 2400 is desirable as the spatial filteringdevice.

FIG. 8 is the composition of the inspection apparatus at the time ofusing the micro-mirror array device 2400 as the spatial filter. Themechanism 601 which branches light path in the middle of an opticalsystem is offered, and it has the sensor 605 which observes the spatialfilter plane simultaneously. A shielding pattern is generated based onthe picture of the Fourier transform plane taken in by the sensor 605,and many micro-mirrors 2400 is driven by a control unit 2410 whichcontrols the micro-mirror array 2400. Diffraction lights which want toshield at this time are reflected in the direction which cannot receiveon sensor 206 b by the micro-mirror array 2400. The light which were notshield are reflected as it is by the mirror array 2400, and the lightare taken in by sensor 206 b. When the image sensor 206 b receivesdiffraction lights generated from a defect, the spatial filter 2000 puton the Fourier transform plane will be removed.

Moreover, FIG. 9 and FIG. 10 illustrate the section of two sorts ofmicro-mirror arrays. The micro-mirror array 2400 is the microelectronicsdevice (DMD) made by being with the semiconductor process etc. Amicro-mirror 2401 supported to a support 2402 being provided on a base2404 is driven by electrostatic attraction and repulsion with electrode2403 being provided on the base 2404. When the system of FIG. 10 whichcan keep optically a flat state by contacting to contact member 2405combines with an image optical system 201, 203, 602, image accuracybecomes high and is desirable.

As shown in FIG. 14, as for the semiconductor, the wiring patternchanges with the functions also in the tip (die). Therefore, thediffraction pattern and the optimal shielding pattern corresponding toit differ for each area A˜D as shown in FIG. 15. Numerical number 11 isshown a area A. Numerical number 12 is shown a area B. Numerical number13 is shown a area C. Numerical number 14 is shown a area D without acircuit pattern.

Although FIG. 16 is a 1st embodiment of the inspection method, it is amethod of inspecting a wafer by matching (aligning) the optimalshielding pattern of the spatial filter with the circuit pattern of thelargest area A (11). Although this method can be inspected in highsensitivity in the area matching (aligning) the filter, other area hasthe subject that sensitivity will become low.

FIG. 17 is a method of inspecting by using a shielding pattern, theshielding pattern 41 being generated by merging (taking logical sum)diffraction of each pattern. Although it can inspect evenly regardlessof the form of patterns if it is this system, the subject referred to asbeing unable to perform inspection of high sensitivity occurs.

FIG. 18 is a method of inspecting two or more times by matching thepatterns 31˜34 of the spatial filter for each pattern A˜D. This methodcan perform inspection of high sensitivity for any area by merging twoor more times of inspection results. However, it is a subject thatthroughput falls in order to carry out two or more inspection. Whenconsidering the strategy of an efficient inspection using the inspectionapparatus with high enough sensitivity for the process of asemiconductor, the inspection method of FIG. 17 is desirable. Moreover,in a case of that it is need to inspect a specific pattern in highsensitivity in the time of introduction of a new process and starting ofa production line etc., the inspection method of FIG. 16 or 18 isdesirable.

FIG. 11 is one embodiment of inspection apparatus equipped with two ormore spatial filter units 2000 a˜2000 d, and if amount of illuminationlight is sufficiently obtained, it will become possible to inspect athigh sensitivity and the high throughput for all areas with this system.Numerical number 601 a˜601 c are branched optical systems. Numericalnumber 201 is a Fourier transform lens (which has a function as anobjective lens). Numerical number 202 a˜202 d are an inverse Fouriertransform lens (which has a function as an image forming lens).Numerical number 203 a˜203 d are a polarizing plate. Numerical number204 a˜204 d are a light intensity adjustment plate. Numerical number 205a˜205 d are a line image sensor (CCD or TDI). FIG. 12 shows a Fourieroptical system 201, 202. FIG. 13 shows the optical system 600 (602, 605)which observes the Fourier transform plane.

FIG. 20 is a figure showing embodiment of a scanning method when takingin diffraction image for one chip, on a case of setting up shieldingpatterns of the spatial filter automatically. As shown in FIG. 21, sincethe pattern of diffraction light is decided with the circuit pattern A˜Dof the chip, it turns out that it changed from predetermined pattern toanother pattern on a chip by seeing (observing) change of thediffraction pattern 21˜24 with the optical system 600 (602, 605). Thatis, the layout information on a chip will be known by paying one'sattention to change of the diffraction pattern 21˜24. Paying attentionto this point, it becomes possible to determine any spatial filtershould be used on certain area, by being taken in the diffractionpatterns for one chip and by investigating each diffraction pattern. Inaccordance with above mention, it becomes possible to set up a spatialfilter automatically by combining image processing with taking in of thediffraction pattern for one chip.

FIG. 22 shows setting sequence of the spatial filter. The diffractionimage 25 is acquired by observing design data, wafer pattern, ordiffraction pattern directly (S50). Then, it becomes possible togenerate the filter pattern should compute by generating the shieldingpattern 35 based on the image processing (S51, S52).

FIG. 23 shows one embodiment of an inspection condition setting sequencein the arithmetic processing system 400 by using monitor 500. S60 is astep for inputting the kind name and the process name of a waferincluding a chip. S61 is a step for inputting the information relatingwith the wafer, the information including wafer size, chip matrix, shotmatrix, chip size, TEG chip, inspection direction (scan line) as shownin FIG. 20, alignment chip and alignment pattern. S62 is a step forsetting up inspection threshold value according to each area A˜D. S63 isa step for setting up inspection/non-inspection areas. S64 is a step forsetting up sensitivity according to each areas. S65 is a step forsetting up shielding patterns of the spatial filter according to eacharea A˜D. Then, S66 is a step for performing a trial inspection 1. S67is a step for setting up the laser power according to each area A˜Dbased on the result of the trial inspection 1. S68 is a step forperforming a trial inspection 2. S69 is a step for reviewing defectcandidate detected by the trial inspection 2. S70 is a step forcorrecting the inspection threshold value set up by the step 62. S71 isa step for performing an actual inspection. S72 is a step for outputtingthe inspection result to the monotor 500 etc. There are described, forinstance, by Japanese Patent Laid-open No. 2000-105203 (equivalent toU.S. patent Ser. No. 09/362,135).

FIG. 24 shows a method for calculating pitch (p) of diffraction lightfrom a pattern pitch (d). p=(f·λ)/d However, f is focal length of thelens 201. λ is wave length of the light.

FIG. 25 shows the signal intensity of the pattern at the time of usingthe spatial filter and at the time of not using it. At the time of notusing it, defect signal cannot detect by separating from the patternsignal. However, as the signal of a pattern is decreased sharply byusing the spatial filter, it becomes possible to acquire the signal of adefect with the high S/N ratio.

FIG. 26 shows the relation of an inspection apparatus 91, 92 and themanufacturing process of the semiconductor device. The wafer afterspecific process passage is inspected with an inspection apparatus 91.It becomes possible to apply feedback to the original process byidentifying the details of a defect with review apparatus 62 etc. afterthe inspection has been performed by the inspection apparatus 91. Itbecomes possible to improve the yield of a semiconductor device by thisrepetition. Numerical number 81 is a process management system formanaging the manufacturing process of the semiconductor device.Numerical number 82 is a defect management system for managing thedefect information obtained from the inspection apparatus 91 and thereview apparatus 62 etc.

As explained above, according to the present invention, in thetechnology of inspecting a minute circuit pattern using the image formedby irradiating white light, single wavelength light, and laser light,the foreign particles and the defect can be detected at high sensitivityby using highly precise spatial filtering.

1. A method for inspecting defects, comprising the steps of:illuminating light to an inspection object containing repetitive circuitpatterns formed on a surface thereof; detecting an image signalcorresponding to transmission light by selectively shielding adiffraction light pattern generated from said repetitive circuitpatterns when the illuminating light is reflected form the surface ofsaid inspection object; observing a Fourier transform image as theselectively shielding diffracted light pattern in a Fourier transformplane; and detecting the defects existing on the surface of theinspection object by processing the detected image signal; wherein saidselective shielding of said diffraction light pattern in said detectingstep is performed by a micro-mirror array device which uses the Fouriertransform image as the selectively shielded diffraction light pattern.2. A method for inspecting defects according to claim 1, wherein saidrepetitive circuit patterns comprise a plurality of area formed on thesurface of said inspection object, and said selective shielding of thediffraction light pattern is performed according to a change of thediffraction light pattern for every area in one chip obtained bydetecting diffraction light patterns for one chip as a Fourier transformimage.
 3. An apparatus for inspecting defects comprising: anillumination optical system which illuminates light to an inspectionobject containing repetitive circuit patterns formed on a surfacethereof; an optical detection system which detects light reflected fromsaid inspection object and transmitted through a shielding unit, andconverts the detected light into an image signal; and a processingsystem which detects the defects by processing the image signal detectedby said optical detection system; wherein said shielding unit isprovided in said optical detection system to selectively shielddiffracted light patterns coming from the repetitive circuit patternsexisting on the inspection object, and said shielding unit comprises amicro-mirror array device, and wherein said shielding unit furtherprovides an optical observation unit which observes a Fourier transformimage as the selective shielding diffractive light patterns in a Fouriertransform place and a control unit which controls each micro-mirroroperation of the micro-mirror array device in accordance with theFourier transform image as the selective shielding diffracted lightpatterns.
 4. An apparatus for inspecting defects according to claim 3;further comprising an optical observation unit which observes a Fouriertransform image as diffraction light patterns for one chip in a Fouriertransform plane, and wherein said repetitive circuit patterns comprise aplurality of area formed on the surface of said inspection object, andsaid shielding unit selectively shields the diffraction light pattern inaccordance with change information of the diffraction pattern for everyarea in one chip in the diffraction light patterns for one chip obtainedby the optical observation unit.
 5. A method for inspecting defectsaccording to claim 1, wherein selective shielding of said diffractionlight pattern in said detecting step is performed by using themicro-mirror array device so that each micro-mirror operation of themicro-mirror array device selective shields the diffraction lightpatterns by reflecting the diffracted light in a direction where asensor for detecting the image signal corresponding to the transmissionlight reflected by each micro-mirror operation cannot receive theselective shielding diffracted light patterns.
 6. An apparatus forinspecting defects according to claim 3, wherein said shielding unitfurther comprises an optical system wherein each micro-mirror operationof the micro-mirror array device selectively shields the diffractionlight patterns by reflecting the diffracted light in a direction where asensor for the detected light reflected by each micro-mirror operationof the micro-mirror array device into the image signal cannot receivethe selective shielding diffracted light patterns.